1. Technical Field
The present invention relates generally to signal transmission, and more particularly to a method of transmitting signals by means of voltage waveforms.
2. Description of Related Art
Typically, indoor electricity wiring is installed by providing two wires between an electricity box on the ceiling and another electricity box in the wall, wherein the two wires are connected to a switch. To install an electric apparatus (such as a lamp, an electric fan, or other loadings), the electric apparatus is fixed on the ceiling and connected to an end of mains electricity, while the other end of mains electricity is connected to a switch through the wires, and connected back to the electric apparatus to form a power loop. In this way, the electric apparatus can be turned on and off simply by switching the switch.
Because of the advancement of technology, electric apparatuses nowadays provide various functions. For example, the luminance and light color of a commonly seen LED (light-emitting diode) illumination system are usually adjustable now. In order to transmit control signals which are related in performing such functions, the LED illumination system may need additional control wiring other than the power loop to transmit the control signals from, say, a control panel on the wall to a LED module.
In other words, additional control wiring seems necessary for LED illumination systems which have functions of adjusting luminance and light color, because control signals may have to be transmitted through control wiring to a LED module. However, additional control wiring inevitably increases the cost for home maintenance or home decoration.
There are two conventional ways to transmit control signals without installing additional control wiring, which are by means of wireless transmission and carrier transmission. The wireless way requires wireless transceivers respectively installed at the LED module and the control panel on the wall, and the control signals for controlling the LED module can be transmitted wirelessly. As to the carrier way, there has to be a modulator to convert control signals into frequency-modulated signals or amplitude-modulated signals, and the converted signals are carried through power line. The LED module can be controlled after the converted signals being recovered with a demodulator.
Either way requires expensive equipment, and wireless transceivers and modulators still need additional power wiring too, which is kind of bothersome. Furthermore, signals transmitted by means of wireless transmission or carrier transmission tend to be interfered by other wireless signals, and it even creates more trouble to comply with EMI and EMS regulations of different countries.